Furnace



a To all 1.01 162% it may concern:

tion, 111 Which-'- UNITED STATES & COMPANY, 1310., orrirrsnunen, rn

SYLVANIA.

Be it known that 1, CHARLES L. WV. Tmnjns, a citizen of the United States, residing at Pittsburgh, Allegheny county, Pennsylvania, have invented a new and useful ln'iprovement in Furnaces, of which the following is a full, clear, and exact description, reference beinghad to the accompanying drawing, forming part of this specifica- Figure 1 alongitmlinal vertical section a of" a heating furnace embodying my invention, and

Fig. 2 is a section on the line 11- 11 of invention has relation to furnaces,

and more particularly to the construction and arrangement of thefurnace hearth, and

a is particularly applicable to heating and annealing furnaces.

Inheating and annealing furnaces it is desirable to have a practically uniform temperature throughout the heating chamber of the furnace. Such furnaces are usually of the underfired type; that is to say having a combustion chamber below the heating chamber for the material and so arranged that the gases of combustion pass from the combustion chamber through the heating chamber. In the latter they give up heat to the chamber walls which, in turn, radiate it back to the material which is being heated. In this manner the material receives heat from all sides and assumes a comparatively uniform temperature.

This type of underfired furnace, as now built, has many disadvantages. It is necessary that the hearth shall be made strong enough to carry the material placed upon it. A metal hearth is exceedingly desirable, not only because it permits amuch quicker heating in the heating chamber; but because it decreases the temperature in the combustion chamber and reduces the heat losses from that part of the furnace. It has not been practical heretofore, in so far as I am aware, to make the hearth of metal because it would not be strong enough above the flame. hen made of refractory material, it must, in order to have the necessary strength, be of such thickness that the temperature in the combustion chamber is so greatly in excess of that in the heating nominee);

PATENT OFFICE; CHARLES LfW. reruns, or rrrrsncneii, rnnusrirvema, assrsnon To rarnmionns rinsrriv anra, a ICORPORATIONOI PENN- T'atented Nov. .23, 1920.

Application filed February 2, 1920. Serial No. 355,759.

chamber that frequently the refractories of the combustion chainberwill melt downbefore the proper temperature has been reached in the heating chamber.

My invention is designed to overcome these difficulties and to enable a metallic hearth. to be employed throughout the entire floor of the heating chamber. I accomplish this object by so arranging the hearth that any desired portion thereof may be protected by just suflicient refractory mate rial to keep it from burning out and keep the flame from being chilled. i

Referring to the accompanying drawings in which I have shown one embodiment of my invention, the nume al 2 designates the wall of a heating furnace of the undcrfircd type, 3 thecombustion chamber at one end of the furnace,- andt the heating chamber.

The combustion chamber may be supplied \Vllll1;1f116l in any usual or suitable manner as by means of the opening shown at 5. y

(3 designates a metallic hearth which forms the entire floor of the heating chamber and whichis supported upon the piers 7. This metallic hearth has its dimensions somewhat less than the interior dimensions of the furnace so that openings will be provided at at least two, and preferably along three edges of the same, as indicated at 8. 9 designates a refractory shield which is placed underneath that portion of the metallic hearth which subjected to the most intense flame from the combustion chamber. This shield is preferably, although not necessarily, provided with a number of perforations or openings 1.0 therethrough which permit a small part of the radiation of the hot flame from the combustion chamber to reach the metallic hearth. This shield is supported upon the piers 11 which are so constructed and arranged as to permit the hot gases to pass upwardly through the openings 8.

The gases escape from the heating chamber through any suitable arrangement of outlet ports, the location of which is immaterial in the present invention.

It will. be readily understood that my inthe appended claims; thus, instead of limitinglthe refractory shield to .the particular portion of the hearth shown, the entire underside, or any desired portion thereof may be; protected by aheat resisting material;

1 and a combustion chamber below the heating chamber, ametallic hearth having a heat resistlng, material immediately underneath V such hearth, substantially as described.

2; In a furnace having a'heating chamber and a combustion chamber below the heating chamber, am'etallic hearth between the two chambers, anda shield of heat resisting material placed above the combustion chamber and underneath the metallic hearth, there being passages for the hot gases around the hearth from the combustion chamber to the heating chamber, substantially as described.

3. In a furnace having a heating chamber 7 and a combustion chamber below the heating chamber, a metallic hearth separating the two. chambers with passages at at least two sides of the hearth connected with said chambers, and a heat resisting material immediately underneath the metallic hearth above the combustion chamber, substantially as described.

l. In a furnace having a heating chamber and a combustion chamber below the heating chamber, a hearth comprising a metallic element, and a shield of heat resisting material placed between the flame and the metallic hearth, said shield having openings therethrough, substantially as described.

5. A furnace of the underfi red type having a metallic hearth provided with heat resisting material immediately underneath a portion of such hearth, sul'istantiully as described.

6. A furnace of the under-tired type having a metallic hearth provided with heat resisting material immediately underneath a portion of such hearth, said heat resisting material having vertical openings therethrough, substantially as described.

7. In a furnace having a heating chamber and a combustion chamber below the heating chamber, a metallic hearth between the two chambers, and a shield of heat resisting-material placed above the flame in the combustion chamber and underneath a portion of the metallic hearth, there being passages leading from the combustion chamber around the edges of the hearth to the heating chamber, substantially as described.

In testimony whereof, I have hereunto set my hand.

CHARLES L. ll. 'lRlXl'S. 

